1. Field of the Invention
Exemplary embodiments of the present invention relate to a non-halogenated etchant and a method of manufacturing a display substrate using the non-halogenated etchant. More particularly, exemplary embodiments of the present invention relate to a non-halogenated etchant for etching an indium oxide layer used for manufacturing a display substrate and a is method of manufacturing a display substrate using the non-halogenated etchant.
2. Discussion of the Background
Generally, a display panel includes a display substrate on which a thin-film transistor (TFT) as a switching element for driving a pixel is formed. The display substrate includes a plurality of metal patterns mainly formed via a photolithography process. In the photolithography process, a photoresist layer is formed on a substrate on which a layer for being etched is formed. After the photoresist layer is exposed by light and is developed to form a photoresist pattern, the layer is etched by an etchant using the photoresist pattern as an etching stop layer in order to pattern the layer.
In etching the layer, the layer in a region exposed through the photoresist pattern is removed by the etchant so that a lower layer disposed under the layer is exposed. Then, the lower layer exposed through the patterned layer contacts with the etchant so that the lower layer may be damaged by the etchant.
Examples of an etchant used for etching a layer including an indium oxide layer include an aqua regia based etchant (Korean Publication No. 1996-2903), an iron chloride based etchant (U.S. Pat. No. 5,456,765), and an oxalic acid based etchant (Korean publication No. 2000-17470). However, the above etchants may have chemically strong activity so that the lower layer under the etched layer may be easily damaged by the etchants. In order to solve the above problem, an etchant composition (Korean Publication No. 2005-77451) including sulfuric acid as a main oxidizing agent and nitric acid or perchloric acid as a sub oxidizing agent has been developed, and the lower layer may not be damaged by the etchant composition when the lower layer includes aluminum-niobium (Al—Nb), molybdenum (Mo), or chrome (Cr).
However, when the lower layer includes a copper (Cu) layer, the indium oxide is layer formed on the lower layer is etched using the etchant composition so that a surface of the copper layer may be damaged by the etchant composition. Thus, the etchant composition may not be used when the lower layer includes the copper layer. Accordingly, an etchant composition for etching the indium oxide layer when the lower layer includes copper may need to have different components from an etchant composition for etching the indium oxide layer when the lower includes aluminum. Therefore, a manufacturer may need to prepare different etchant compositions depending on the composition of the lower layer, thereby increasing a manufacturing cost.